Multiple cavity resonator



Au 12, 1952 L. BRU CK MULTIPLE CAVITY RESONATOR 2 SI-lEETS-SHEET 1 FiledAug. 24, 1948 INVE'NTOR AGENTS Aug. 12,1952 L. BRUCK MULTIPLE CAVITYRESONATOR 2 SHEETSSHEIET 2 Filed Aug. 24, 1948 INVENTOR L QJH R s 3v)? mL AGENTS Patented Aug. 12, 1952 Lothar Briick, Paris, France, assignorto Compagnie Generale de Telegraphic Sans .Fil, a. cr-,

poration of France Application August 24, 1948, SerialNo.45585 In FranceAugust28, 1947 7 Claims.

The present invention relates to a multiple cavity resonator of a typewhich may be used to particular advantage in a klystron of the reflextype.

According to one feature of the invention, the said resonator isprovided with a plurality of reentrant portions which may be mutuallycoupled :by loops known as strappings;

For the purpose of establishing a klystron of great power, :it is knownto locate a plurality of electronic systems in mutual proximity insidethe same tube. The resonator circuit (or circuits) is then constitutedby a cavity with a plurality .of ;re-entrant portions. The maximumelectrical field corresponding to the required wave is always found atthe summits of the reentrant portions. .A large cavity of this naturemay be considered as being partitioned ,by the Walls of each re-entrantportion and divided into a plurality of small cavities which arevmutually coupled by their magnetic fields. The fields of adjacentcavities are opposed in phase, but there are many cases where thismethod of coupling is too loose. If the coupling could be tightened, onthe one hand the required wave could be advantageously discriminatedfrom the parasite or disturbance waves (and it is known that there areseveral .such waves in a-klystron having .a multiple cathode associatedwith :a multiple cavity), and .it would be very .much easier to changethe resonance frequency. .Furthermore, the output efiiciency of the tubewould be improved.

One object of the invention is to provide coupling means for multiplecavity resonators whereby these advantages are-achieved and theelemental cavities are more tightly coupled to each other.

Another object is to provide a multiple cavity resonator equipped with adevice for coupling the elemental cavities thereof.

In the accompanying drawing:

Figure 1 shows a multiple cavity seen in perspective, part of the wallhaving been removed to give a view of the inside of the cavity;

Figure 2 is a plane view of the cavity of Figure 1;

Figures 3 and 4 are plan views of cavities with difierent couplingdevices;

Figure 5 is a longitudinal section in a radial plane of the cavity andtuning system;

Figure 6 is a plan view of a cavity with a larger number of elementalcavities;

Figure '7 is a plan view of a cavity with capacitive coupling;

Figure .8 is a 1view.-similar to Figure "5 ;but 01 the device of 7,;

Figure '9 is a partial view in perspective showing the arrangement of :acavity according to theinvention inside a k-l-ystron tube.

In Figural, a cavity -K comprises .re-entrant portions 1 to 6 which arearranged in a :circle, as seen also in Figure 2, and which defineelemental cavities. .In the vicinity of teach reentrant portion isarranged a coupling loop 10;- strapping and connections are -.established between the loops located near cavities ofgsame phase. Figuresland -2 show an arrangement of 6 ,re-entrant portions. At all-times thecay ities near e1ements-l-3--5 are of same ;-phase as alsothosenearelements 2--4- -6 in opposition thereto. By means of loops or.strappings Si and S2 the cavities at 1-3-5 and at '24-6 arerespectively coupled. Without these-loops, the cavity at '3 would be:coupled only to the adjacent cavi-tiesat Land 14. But with the-loop, itis coupled also to -the cavities at I and =at5 Hence the total couplingof the cavities :is :considerably tighter.

According to .the desired rate of coupling, it is possible to use onlyone coupling :star S -or two stars S1 and S2 coupled together; For ex.-ample, only the :ca-vities :occupying even-numbered positions maybecoupled.

Instead of .coupling stars, triangles may .be used, either one or two,.as shown by S1 .andfia in Figure vWhere :the apicespfon triangle arelocated :all in even-numbered or all in oddnumbered cavities. g I

In the device .of Fi ure 4. one set of cavities is coupled ;by atriangle, and the .other .set- -by a star, .but here .the couplingbetween the strappings is looser than 'inFigures 1 to :3. s I

With the type of coupling so :iar described, it-is possible to obtain agood flow 10f. .decimetric energy as well as greater ease of frequencyvariation. Figure 5 :shows :one example of construction wherein a groupof cavities incIudi-ng the one near element 4 is coupled by a triangleor star S2 visible "on figures '1 to 4 but not shown on Figure 5. Thecavities of the other group including the one near element I are coupledtogether by a star, the center of which is connected to the interiorlead of a coaxial line L. The flow of energy occurs simultaneously fromall three elemental cavities. By means of piston K, the line may beadapted to any desired impedance which is then communicated as aparallel impedance in the elemental cavities through the branches ofcoupling star S1. In this manner, the cavities can be tuned and theirresonance changed. This coupling device adds a variable impedance to oneout of two elemental cavities, and the range of possible frequencyvariation is greater than with a coupling involving only one elementalcavity.

Obviously this type of coupling is not limited to six re-entrantportions and can be used with 4, 8, 12, etc., and where there are 8 ormore elemental cavities, the coupling can be either polygonal as inFigure 6 or by stars with interconnected points as in Figure 7.

It is also possible to use capacitive instead of inductive coupling. Inthis case, instead of the coupling loops comprising curved ends coupledinductively to the cavities, the device comprises,

for the purpose of coupling, only the single.

capacity existing between the respective surfaces of the loops and ofthe cavities. In Figure 8, which corresponds, for the sake of example,to a section of Figure 7, there is shown a single loop S1 supported byan insulator i. The power outlet can, for example, be extracted throughaxial line L passing through insulator 2'. Figure 9 shows a partial viewof a device, according to the invention, incorporated in a reflexklystron seen in perspective and broken away through the center. Thistype of klystron is known as multi-canon. Re-entrant portions I, 5, 4and 6 are clearly shown to have a conical shape since the strictcylindrical shape is not necessary for the purpose of the invention.Cathodes C are heated by filaments f, and there are provided reflectingelectrodes R, the whole device being contained in an envelope E. Loop S1is connected to concentric line L for the purpose of extracting energy.

Itjwill be understood that the embodiments described are given by Way ofillustrative example and that it is 'not the purpose of this descriptionto limit the invention which is fully covered by the scope of theappended claims.

What I claim is:

1. Electronic tube for ultra high frequency and super high frequencycomprising at least one cavity resonator in the form of a hollow bodybounded by a surface comprising a plurality of re-entrant portionsdividing the interior of the cavity into partial cavities, means forcausing an electronic beam to traverse each re-entrant portion, meansfor producing fields of difierent phases in the partial cavities, afirst coupling .member having integral portions extending into proximityto a first group of partial cavities in which fields of the same phaseare produced, and a second coupling member having integral portionsextending into proximity to a second group of partial cavities in whichfields of the same phase are produced out of phase with respect to thefields produced in said first group of partial cavities, therebyinductively coupling together those partial cavities in which fields ofthe same phase are produced.

2. Electronic tube for ultra high frequency and super high frequencycomprising at least one cavity resonator in the shape of a hollow bodybounded by a surface comprising a plurality of re-entrant portionsdividing the interior of the cavity into partial cavities, means forcausing an electronic beam to traverse each re-entrant portion, meansfor producing fields of difierent phases in the partial cavities, meansinductively coupling together a first group of partial cavities in whichthe field is of one phase, means inductively coupling together a furthergroup of partial cavities in which the field is of same phase, differentfrom that of said first group, and means inductively coupling togetherboth said coupling means.

3. Electronic tube for ultra high frequency and super high frequencycomprising at least one cavity resonator in the shape of a hollow bodybounded by a surface comprising a plurality of re-entrant portionsdividing the interior of the cavity into partial cavities, means forcausing an electronic beam to traverse each re-entrant portion, meansfor producing'fields of different phases in the partial cavities, meansinductively coupling together those partial cavities in which the fieldis of the same phase, and means for extracting energy from the tube,said last named means being inductively coupled to said coupling means.1 I

4. A tube according to claim 1 wherein at least one of the couplingmembers comprises a 'metallic part in the form of a star having aplurality of branches, extending as far as the related partial cavities,having fields of the same phase.

5. Tube, according to claim 1, wherein at least one of the couplingmembers comprises a metallic part in the shape of a polygon, the sidesof which traverse the partial cavities having fields of the same phase.1

6. A tube, according to claim 1, wherein at least one of the couplingmembers comprises a metallic part in the shape of a star having'aplurality of points extending as far as the related partial cavitieshaving fields of the same phase, the ends of the points of the starbeing interconnected by metallic connecting pieces.

7. Electronic tube for ultra high frequency and super high frequencyaccording to claim 1; wherein each of said integral portions of thefirst and second coupling members consists of a curved metal partextending into the related partial cavity.

LOTHAR BaiicK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,284,405 McArthur May 26, 19422,381,320 Tawney Aug. '7, 1945 2,407,667 Kircher Sept. 1'7, 19462,408,409 Bowen Oct. 1, 1946 2,411,151 Fisk Nov. 19, 1946 2,414,085Hartman Jan. 14, 194'?

